In standard encoding schemes for moving pictures starting with H.264/AVC, chrominance elements in input video which have been downsampled when compared to the luminance elements (namely, which have been sampled at a lower frequency than the frequency at which the luminance elements were sampled) are used. This corresponds to video formats known as 4:2:2, 4:2:0, and 4:1:1 formats.
Video formats in which these chrominance elements are resampled are based on the physiological finding that visual sensitivity is less sensitive towards chrominance elements than towards luminance elements, and have been introduced with the aims of reducing the amount of video information and lowering the cost of imaging devices (see, for example, Non-patent documents 1 and 2).
On the other hand, because of increased expectations for further improvements in video image quality, 4:4:4 format video in which chrominance signals are not resampled is attracting attention. For example, in the JVT (Joint Video Team), development for a new profile for H.264 (advanced 4:4:4 profile) is underway.
Non-patent document 1: “Chrominance Signal Interpolation of YUV4:2:0 Format Color Images”, Hiroshi Sugita, Akira Taguchi, IEICE (The Institute of Electronics, Information and Communication Engineers) Transactions, Vol. J88-A, No. 6, pp. 751-760, 2005
Non-patent document 2: “A Color Image Compression Scheme Based on the Adaptive Orthogonalized Transform - Accelerated by Sorted Dictionary”, Takashi Miura, Fumihiko Itagaki, Akihiko Yokoyama, Momoe Yamaguchi, IEICE (The Institute of Electronics, Information and Communication Engineers) Transactions, Vol. J85-D2, No. 11, pp. 1672-1682, November 2002